Apparatus for medical treatment

ABSTRACT

An apparatus for effecting hyperthermia in a narrow body cavity or duct including: a disposable first part ( 1 ) having an elongate distal section ( 5 ) intended to be inserted into the cavity or duct having a centrally located, heat-releasing element ( 22 ), which is either surrounded by an elongate housing ( 24 ) or is itself constituted by an elongate housing, and a flexible and/or elastic enclosure ( 23 ) surrounding the housing in a liquid-tight manner, further including a device for supplying energy to the heat-releasing element ( 22 ) and an axially operating first inlet ( 135 ) at the proximal part of the housing, an outlet ( 133 ) from the housing being arranged for the supply of heat-transmitting medium under pressure for expansion of the flexible enclosure ( 23 ) to accommodate and to exert a controlled pressure on surrounding walls of the cavity or duct, a second inlet ( 131 ) to the housing ( 24 ), and medium-actuating device ( 13, 19 ) for the expansion of the flexible enclosure ( 23 ) and for internal circulation of the medium through the housing ( 24 ); and a permanent non-disposable second part ( 51 ) having a drive ( 55, 75 ) for the device ( 13, 19 ) for expansion and for internal circulation, and a connection ( 43, 59; 41, 81 ) for releasably interconnecting the drive ( 55, 75 ) and the device means ( 13, 19 ) for expansion and internal circulation.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an apparatus for effecting hyperthermiain a narrow body cavity or duct. The invention is especially applicableto the treatment of the endometrium of the uterus. The treatment residesin a combination of the supply of heat to said body cavity or duct andsimultaneous application of a controlled pressure on surrounding tissue.

2. Background Art

In the treatment of certain disorders in narrow body cavities or ductsthe supply of heat is frequently used, the treatment residing in socalled hyperthermia. For use in such treatment several apparatuses havebeen described including a special catheter employing a balloon attachedto the distal end of the catheter. In the treatment of for examplemenorrhagia the distal end of the catheter including the balloon isinserted into the uterus cavity via vagina and cervix, the balloon beingthem then expanded using a pressure medium up to a suitable pressure.The catheter includes heat-releasing means, for example an electricresistance element, to which electric energy is supplied from theexterior via the catheter, the generated energy and the temperaturebeing controlled in different ways (see for example PCT/US89/03916).

In copending application PCT/SE92/00645 there is described an apparatusfor carrying out hyperthermia involving the use of a heat-releasingelement which is of an inherently self-regulating type. Examples of suchelements are elements based on materials of the PTC-type orferromagnetic materials where the means for the supply of energy arebased on magnetic induction. In accordance with said PCT-application theproblem of creating sufficient power output while avoidingself-inhibition associated with a heating element of theself-controlling type has been solved by arranging the element in asurrounding elongate housing through which the heat-transmitting mediumis forced through and around the element by efficient internalcirculation. Such internal circulation around and through theheat-releasing element is generated by providing a reciprocatingmovement of a small quantity of the pressurized quantity of heat-medium.

For details concerning this background art reference is made to theabove-identified patent application PCT/SE92/00645, the full disclosureof which is incorporated herein by reference.

In apparatuses as those described above the balloon catheter is thusconnected to sources for the supply of a liquid medium, electric energyand means for the control of the temperature and the supply of energy.In the apparatus according the above-mentioned PCT-application no meansfor temperature control are necessary but means for the generation of areciprocating movement of a small quantity of the liquid medium will berequired.

In the device according to the above PCT-application the liquid mediumtransferring heat to the area to be treated is in the form of a sterileliquid enclosed in a catheter, the distal part of which carries adistensible enclosure or balloon intended to be inserted in for examplea uterus cavity. Due to this arrangement it is clear that not only theexterior parts of the catheter but also the interior thereof must becapable of cleaning and sterilization after use in view of the fact thatleakage can result in infection of the enclosed liquid and thereby alsothe catheter parts. Even if a catheter is of a disposable type and isdisposed of after use the means connected to the catheter, such as themeans for generating pressure and internal circulation, will have to becleaned and sterilized after every use since they have been in contactwith the liquid medium. Such cleaning and sterilization is a verycomplicated and expensive procedure.

SUMMARY AND OBJECTS OF THE INVENTION

The present invention has for an object to provide a system meeting andrequirements as to sterility.

Another object of the invention is to provide an apparatus where anyrisk of contamination from a preceding treatment is excluded.

Yet another object of the invention is to eliminate the risk forcontamination and transfer of infection at a low cost for eachtreatment.

Still another object of the invention is to enable control andadjustment of the optimum average pressure during the course oftreatment.

A further object of the invention is to provide a system through whichexcessive pressures hazardous to the patient can be avoided.

These and other objects will be obtained in accordance with the presentinvention by an apparatus for effecting hyperthermia in a narrow bodycavity or duct, said apparatus being composed of a first disposable partcomprising all constructional details subject to contamination, and apermanent non-disposable second part comprising the equipment necessaryfor operating the apparatus.

Accordingly, the present invention provides an apparatus for carryingout hyperthermia in a narrow body cavity or duct, said apparatuscomprising:

a disposable first part comprising an elongate distal section intendedto be inserted into said cavity or duct comprising a centrally located,heat-releasing element, which is either surrounded by an elongatehousing or is itself constituted by an elongate housing, and a flexibleand/or elastic enclosure surrounding said housing in a liquid-tightmanner, further including means for supplying energy to theheat-releasing element end an axially operating first inlet at theproximal part of the housing, an outlet from the housing being arrangedfor the supply of heat-transmitting medium under pressure for expansionof the flexible enclosure to accomodate and to exert a controlledpressure on surrounding walls to said cavity or duct, a second inlet tothe housing, and medium-actuating means for said expansion of theflexible enclosure and for internal circulation of said medium throughthe housing; and

a permanent non-disposable part comprising drive means for said meansfor said expansion and for internal circulation, and connecting meansfor unfastenably interconnecting said drive means and said means forexpansion and internal circulation.

In a preferred embodiment of the apparatus of the invention saidmedium-actuating means comprise a first means for the expansion of theflexible enclosure and a second means for the internal circulation ofthe medium.

It is particularly preferred that said first means for the expansion ofthe flexible enclosure by introduction of heat-transmitting mediumthereto is capable also of bringing the enclosure into a collapsedcondition enabling withdrawal of the instrument from the body cavity orduct.

It is preferred that said second means involves the use of areciprocating element creating a reciprocating motion to a determinedquantity of pressurized medium. Said reciprocating element is suitablypart of an injection syringe, although it is conceivable to use othertypes of reciprocating elements, such as a bellows or a deformablenon-elastic container, as will be illustrated in the followingdescription of preferred embodiments.

Said first means for the expansion of the flexible enclosure maylikewise be constituted by an ordinary injection syringe, but also inthis case the syringe can be replaced by other devices capable ofperforming the same function, which is also illustrated more in detailbelow.

For the creation of a reciprocating motion to said reciprocating elementit is suitable to use a device comprising an eccentric capable ofconverting a rotary motion to a rectilinear motion.

Said means for expansion and for internal circulation can be eitherconstituted by two different syringes separately operable for expansionon the one hand and for internal circulation on the other hand. As analternative one and the same syringe can be used for providing bothexpansion and internal circulation, thus simplifying the construction.

According to still another aspect of the invention the apparatus can besupplemented with a pressure control system residing in a seconddistensible enclosure, the interior of which is in communication withthe interior of said flexible enclosure, whereby any undesired pressurearising in the flexible enclosure will be released through distention ofsaid second enclosure.

In such embodiment it is preferred that the second enclosure has ahigher resistance to distention than the flexible enclosure associatedwith the distal part of the catheter.

In a preferred embodiment of such supplemented apparatus there isarranged a non-elastic container surrounding the second enclosure, andsuch container is suitably provided with means for controlling thepressure within the container and outside of the second enclosure. Inthis manner the level of release of an arising excessive pressure can beadjusted.

In the above-identified PCT/SE92/00645 application a number ofembodiments relating to the internal circulation system are described.Furthermore, said application describes different types ofheat-releasing elements, a preferred type being a heat-release elementbased on a PTC-material. For details regarding such features referenceis made to said PCT-application.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will in the following be further described by exemplifyingembodiments which, however, must not be construed to restrict the scopeof protection except as defined in the appended claims. Theseembodiments are described in connection with the appended drawings,wherein:

FIG. 1 diagramatic illustration of a disposable first part of anembodiment of the apparatus according to the invention;

FIG. 2 is a diagramatic representation of combined disposable first partand permanent non-disposable part of the apparatus the presentinvention;

FIG. 3 is an enlarged side-view of a detail of the embodiment of FIG. 2;

FIG. 4 is an enlarged side-view of another detail of the embodimentshown in FIG. 2;

FIG. 5 is an enlarged side-view of a detail of the part shown in FIG. 4;

FIG. 6 is a side-view of an alternative arrangement using only onesyringe for both expansion and internal circulation;

FIG. 7 is a section along line A—A of FIG. 6;

FIG. 8 shows in enlargement a longitudinal section through the centralbody 21 of the embodiment shown in FIGS. 1 and 2;

FIG. 9 shows a corresponding section of an alternative embodiment of thecentral body 21 of the embodiment shown in FIGS. 1 and 2;

FIG. 10 shows a side-view of an embodiment alternative to that shown inFIG. 3; and

FIG. 11 is an embodiment alternative to that shown in FIG. 4.

FIG. 12 shows a diagram on the present/volume relation in using apressure control device; and

FIG. 13 shows an embodiment of the device of the invention harbouringsuch a pressure control system through which hazardous excessivepressures can be avoided.

DESCRIPTION OF PREFERRED EMBODIMENTS

An embodiment of the apparatus according to the present invention isshown in full in FIG. 2, whereas the disposable first part thereof isshown in FIG. 1. Said disposable first part 5 7includes a catheter part3 and a distal part 5 for the application of heat and pressure at thesite of treatment, in the present embodiment the uterus cavity.

The distal part 5 includes a central body 21 comprising a housing 24 andharbouring a heat-releasing element 22, both having an elongateconfiguration. The central body 21 is surrounded by a thin flexible andelastic enclosure or balloon 23, which is distensible under theinfluence of a pressure medium supplied to the interior of saidenclosure 23 in a manner to be illustrated below.

The disposable first part 5 7is furthermore provided with a proximalpart comprising conduit means 9 with a first three-way valve 11 and afirst attachment stud 12. As shown in FIGS. 1 and 2 conduit means 9contains an access pipe 10 for the accomodation accommodation ofelectrical leads extending up to the heat-releasing element 22. Saidleads are suitably connected to a voltage source, such as rechargablerechargeable low-volt batteries. Said conduit means 9 additionallyincludes a side-conduit 16 attached at its end to said first three-wayvalve 11 and including a second three-way valve 15 and an associatedsecond stud 14. At the other end side-conduit 16 contains a leak-tighthousing 18 having an elastic membrane to which a pressure sensor can beattached from the outside for pressure control purposes.

Proximal part 9 further includes two injection syringes 13,19 for apurpose to be described below. Each syringe 13,19 is provided with ahousing or body 25 and 27, respectively, and their respective frontdispensing ends 29 and 31, respectively, are leak-tightly connected tostuds 12 and 14, respectively. Syringes 13,19 are furthermore providedwith conventional pistons 33,35, respectively, each piston having itspiston bar 37 and 39, respectively, and actuating plates or discs 41 and43, respectively. Finally, syringe housings 25,27 are each provided withan outer circumferential flange 45 and 47, respectively.

As previously indicated FIG. 2 illustrates the assemble apparatusincluding the disposable first part 7 and a non-disposable part 51 forrepeated use. Said non-disposable part 51 includes support or platform53 onto which the different parts of the auxillary equipment areattached.

As seen in FIG. 2, syringe 19 is associated with drive means 55, whereassyringe 13 is associated with drive means 75.

Referring now to FIGS. 4 and 5 drive means 55 for syringe 19 include apiston bar actuator 57 slideably mounted on platform 53 in the directionof arrows a). Actuator 57 includes a connecting element 59 with a slot61 for receiving actuating plate or disc 43. Furthermore, actuator 57contains a through-hole 63 for a threaded bar 65 having an operating nob67 at its free end and rotatably but axially fixed at its other end.Finally, actuator 57 is provided with a side-opening 69 containing aradially displacable threaded element 71, the function of which isexplained further below.

As seen in FIG. 4 syringe 19 is arranged on a bed 56 attached to a plate59 which in turn through a spacer 68 is attached to platform 53. Bed 56is provided with a slot 60 for receiving the outer circumferentialflange 47 of syringe 19.

FIG. 3 illustrates in more detail drive means 75 associated with syringe13. Again, syringe 13 is arranged on a bed 73 attached to the upper sideof platform 53 and is provided with a slot 74 for receiving the outercircumferential flange 45 of syringe 13. Said drive means 75 areprovided with an actuator 77 for piston bar 37 of syringe 13. Actuator77 is slideably mounted on platform 53 in the direction of arrows b),and has an upper part 81 provided with a recess or slot 79 for receivingactuating plate or disc 41 of syringe 13. Actuator 77 is furthermoreprovided with a lower part 83 linked to a rotating excenter disc 87 viaan arm 85.

FIGS. 6 and 7 disclose an alternative embodiment of the apparatus of theinventions wherein syringes 13 and 19 are replaced by one single syringecapable of performing two functions as will be described in theoperation of the apparatus below. This alternative arrangement accordingto FIGS. 6 and 7 has the single syringe 13 arranged axially slideable ona bed 89 and contains as before an outer circumferential flange 45.Drive means 75 correspond closely to those described in connection withFIG. 3.

In this alternative embodiment there is arranged an alternative drivemeans 55′ largely corresponding to drive means 55 illustrated in detailin FIGS. 4 and 5 but performing the same function in a different manner.Drive means 55′ are provided with an-upper part 91 extending aboveplatform 53 and provided with a slot 93 receiving flange 45 of syringe13. Its lower part 57 corresponds functions-wise to actuator 57according to FIGS. 4 and 5. Actuator 57 with its upper part 91 isslideably arranged in platform 53 in the direction of arrows a).Threaded bar 65 is rotatably arranged but axially fixed in a block 66attached To platform 53 underneath thereof. The remaining parts of drivemeans 55′ are designed and perform in the same manner as described inrelation to drive means 55 of FIGS. 4 and 5. FIG. 7 shows anillustrative cross-section along line A—A in FIG. 6.

FIGS. 8 and 9 show two embodiments of the central body 21 including theheat-releasing element 22 and the flexible or elastic enclosure orballoon 23 according to FIG. 1.

FIG. 8 shows a detail a system from enabling effective heat transportand heat transfer from the heat-emitting element 119 to the uterusmucosa (endometrium). Element 119 contains wires 115 for electricalresistance heating thereof. Wires 115 are supplied with electric energyvia leads 116 entering through canal 135. Apertures 131 in the proximalpart of the tubular central body operate as radially acting inlets for apressurized liquid medium to a valve housing 132 communicating with aninlet canal 135, the space between central body 21 and enclosure 23, aswell as with canals 121 arranged about and through the heat-emittingelement 119 in the middle part of the central body 21. Apertures 133arranged in the distal part of the central body 21 act as outlets forthe pressurized liquid medium from a second valve housing 139communicating with canals 121 and the space between the central body 21and the elastic enclosure 23, said enclosure being liquid-tight sealedaround the proximal part of the central body at 151 and being attachedto a nose member 141 of the central body. In valve housing 132 backvalves 149 are arranged so as to close apertures or openings 131 atover-pressure in the valve housing 132 and opening at a sub-pressurerelative to the liquid pressure in the space between central body 21 andthe elastic enclosure 23. A partition 143 having openings 145 isarranged in valve housing 139. A disc valve 147 is moveable in an axialdirection and arranged so as to close openings 145 at over-pressure invalve housing 139 relative to the liquid pressure in canals 121 in theheat-emitting element of the central body or opening at sub-pressure invalve housing 145, respectively.

FIG. 9 shows in detail a central body 21 containing heat-releasingelements 157 of an inherently self-regulating type, such as PTC-materialor ferromagnetic material having a Curie point. Element 157 alsocontains canals or passages 121, and said elements 157 and canals 121are surrounded by a housing 29. In other respects the embodiment of FIG.9 corresponds to that of FIG. 8 but with the difference that the discvalve 147 and the associated partition 143 with apertures 145 are nowarranged in the proximal part of central body 21. Between the inlet sideof the wires 153 and the partition 143 a chamber 155 is arranged.

FIG. 9 shows how the liquid medium is forced to circulate into chamber145 and further in through the wire package 157 at a pressure shock atthe same time as valves 149 close apertures 131.

The procedure for performing hyperthermia in a uterus cavity using theapparatus described above including the function of said apparatus willnow be explained more in detail.

The disposable first part 7 can be stored in a sterile package separatefrom the stationary part up to the time of treatment when it isassembled with the stationary part 51 in the manner indicated above.Although said disposable first part 7 contains a number of elementsperforming the necessary functions for the operation of the apparatusaccording to the invention it is interesting to note that all partsthereof, in order to obtain a disposable assembly, can it be produced inlarge series at a direct cost not amounting to approximately more thanbetween say 25 and 50 USD.

At preparation for treatment the syringe 19 is filled with somewhat morethan the quantity of sterile liquid medium required to fill up thesystem and is then connected to stud 14. By maintaining the disposablepart 7 in a vertical position with syringe 19 in a vertical uppermostposition and imparting short movements to piston 35 of syringe 19 thesystem will be filled with liquid and at the same time air can beremoved from the system and collected in syringe 19. Syringes 19 and 13can easily be freed from air by disconnecting them from the system.Syringes 19 and 13 are then connected to their respective studs andpiston of syringe 19 is positioned so that the enclosure 23 remains in acollapsed condition. The distal part 3 of the applicator is theninserted through vagina, cervix and into the uterus cavity up to thebottom of the cavity. The length of the central body 21 correspondsapproximately to the length of the uterus cavity, i.e. normally 4 to 6cm. Next, syringe 19 is attached with its operating end to drive means55 by inserting disc 43 into slot 61. Syringe 13, partially filled withliquid, is attached with its rear operating end to drive means 75 byinserting disc 45 into slot 79. Three-way valves 11,15 are set so as toestablish communication between syringes 19 and 13 and the interior ofenclosure 23, and piston 35 is pushed forward within syringe 19 toexpand the flexible enclosure 23 to conform to the surrounding uteruswall. Piston 35 is pushed forward until the desired pressure is reachedas recorded by the pressure sensor.

As seen in FIGS. 4 and 5 drive means 55 can be used for free movement ofpiston 35 in syringe 19 by retracting threaded element 71 to theposition shown in FIGS. 4 and 5. On the other hand, by pushing threadedelement 71 into engagement with the threaded bar 65 fine adjustment ofthe position of piston 35 can be attained by rotating nob 67, wherebyfine adjustment of the pressure in the system can be attained.

After the filling procedure drive means 75 are started imparting to thepiston 33 of syringe 13 a reciprocating motion. At every positivepressure shock a certain volume of liquid is brought to move forwardthrough the conduits up to the inlet canal 135 of the central body (FIG.8). This has for an effect that simultaneously a corresponding quantityof pressurized liquid medium is forced through canals 121 in the centralbody 21 in view of the fact that valves 149 are closed at the same timeas valve 147 is opened, and a corresponding quantity of pressurizedliquid medium will be pushed out into the space inside the flexibleenclosure 23.

At every subsequent backward movement of the piston of syringe 13 acorresponding quantity of liquid medium will be sucked back, valves 149taking the open position shown in FIG. 8 and valve 147 its closedposition. It is appreciated that under the influence of the oscillatingpressure shocks and the described valve system a powerful and effectivecirculation in an internal flow circuit of liquid medium at the pressuregiven by syringe 19 will be provided through canals 121 of the centralbody 21 and out into the space within the balloon enclosure and back tothe central body without hot liquid passing the inlet canal 135 of thecatheter to the other parts of the apparatus. Thus, circulation takesplace only in the distal part of the apparatus, whereas the inlet canal135 during circulation only serves as a communication conduit fortransmitting in a hydraulic manner the oscillating pressure and liquidmovement provided by syringe 13 and for maintaining the desired pressurein the system by means of syringe 19.

In the treatment using the apparatus according to the present inventionthe pressure used in the system varies from case to case and may alsovary during the treatment of one and the same patient, in view of forexample variations in blood pressure, contractions of muscular tissueetc. A suitable pressure range lies within the interval between about120 and about 170 mm Hg, and a suitable temperature of the circulatingliquid is about 65° to 90° C. The period of treatment for obtaining thedesired result varies within relatively wide limits but satisfactoryresults are usually obtained with a time of treatment varying from about20 to about 30 min.

In order to obtain satisfactory internal circulation it has been foundthat a reciprocating frequency for the means for internal circulationlies between about 300 and 1000 strokes per min at a stroke volume ofabout 0.1 to 0.5 ml. It is to be noted that these values are to beconsidered only as suitable guidelines and other values lying outside ofthe ranges given are fully conceivable.

By considering the illustrations of FIGS. 1 and 2 it is appreciated thatFIG. 2 shows the disposable first part 7 which, after use, can bedisconnected from the non-disposable stationary part 51 and is thentransferred to a destruction site so that infection throughcontamination can be avoided. The stationary part 51 will be completelyfree of any contamination and can be used repeatedly.

The stationary part 51 can additionally contain sources of electricenergy, electrical leads and it can also contain a unit for the controlof pressure, temperature and time and suitable displays for visualizingthe corresponding parameters.

The embodiment shown in FIGS. 6 and 7 using only one syringe 13 forperforming both filling and pulsating functions operates in a similarmanner, although expanding the enclosure is performed by operating drivemeans 55′ to move the body or housing 23 of syringe 13 relative to thepiston 33 and the bed 89 in an axial direction. After the expandingoperation the body 25 of syringe 13 is maintained in a fixed position bybringing threaded element 71 in engagement with the threaded bar 65,whereafter drive means 75 is started to perform the function ofproviding internal circulation in the same manner as the device shown inFIG. 3.

FIG. 10 shows an arrangement which constitutes an alternative to theembodiment shown in FIG. 3. This alternative drive means 75 is arrangedon platform 33, and syringe 13 of FIG. 3 has been replaced by a device36 comprising an elongate hollow body 32 and, attached at the rear endthereof outside of flange 45, a bellows 46 which at its rear end in turncarries actuating plate or disc 41.

Operatively, the device of FIG. 10 operates in exactly the same manneras the arrangement described in connection with FIGS. 2 and 3 to providefor effective circulation in an internal flow circuit of liquid medium.

In FIG. 11 there is shown an arrangement which constitutes analternative to the embodiment shown in FIG. 10, where syringe 13 of FIG.3 has been replaced by another device 38. Driving device 75 as shown inFIG. 3 is not illustrated in FIG. 11 except element 59 that has beenmodified to match new device 38 replacing syringe 19.

Device 38 contains a hollow elongate body 34 having an exteriorcircumferential flange 45 engaging a slot in bed 57 in the same manneras shown in FIG. 3. At the rear end of body 34 there is arranged aflexible inelastic container 48 which is connected to element 59 ofdrive means 55 through a bar 50 having at its free end a ball 52 fittinginto a recess 54 of element 59.

The device shown in FIG. 11 can thus be used to replace syringe 13 shownin FIG. 2 using the eccentric device of FIG. 3 for providingreciprocation of element 59 resulting in internal circulation aspreviously described. In such pulsation, container 48 of FIG. 11 movesbetween the position shown in full line and the position shown in dottedline at 42.

Even if an indicated above there are alternative embodiments, whereinthe syringe 19 and 13 according to FIG. 1 have been replaced with otherdevices illustrated in FIGS. 10 and 11, the embodiment according to FIG.1 involving syringe 19 is preferred. On the one hand, such syringes canbe massproduced at a very low cost and, on the other hand, as alreadydescribed such a syringe can easily be deairated and filled with liquid,respectively, through an operation well known to the operator.Furthermore, syringe 19 can be graduated, such as with a milliliterscale, so that the operator will know the quantity of liquid injectedinto the system.

When using drive means 55′ and 55′, according to what has bee describedin connection with FIGS. 4 and 5 and FIG. 6, respectively, fineadjustment of the system pressure can be made, and practice has alsoshown that this is necessary.

As earlier described the distal section 5 of the device, the enclosurebeing in a collapsed condition, is inserted into the uterus cavity,piston 35 of syringe 19 being then pushed forward to expand theenclosure. As long as the expansion takes place without the walls of theenclosure touching the walls of the cavity the expansion takes place ata low pressure depending inter alia on the elastic properties andthickness of the material of the enclosure. As a rule a highly elastic,thin enclosure material is desirable in order to obtain maximumcompliance with the irregular inside surface contour of the uteruscavity while offering at the same time efficient heat transfer from theliquid medium to the endometrium.

To the extent that the enclosure in its expansion comes into engagementwith the major part of the interior surface of the uterus cavity theresistance of the uterus muscle towards expansion will increase, thepressure in the system increasing at a higher rate for every volume ofliquid injected. Pressure versus volume is indicated in FIG. 12. Curve 1in full line shows said relation in the free expansion of a thin-walledelastic enclosure suitable for the treatment of uterus in accordancewith the present invention. As seen from the figure a certain initialpressure (about 70 mm Hg) will be required for a first small expansion(about 1 ml). Then the expansion takes place at a slowly increasingpressure (about 70-100 mm Hg) that can be designated the plateaupressure. As earlier mentioned the curve will take another shape whenthe enclosure is brought to expand in for example a uterus cavity.

FIG. 12 shows two curves A-C and B-D with dashed lines thepressure/volume relation with two different cavity sizes. As seen fromthe figure the curves increase quite steeply depending on the resistanceof the uterus muscle. According to the invention it is intended to openthe cavity by expansion of the enclosure so that the whole interiorsurface of the cavity will be subjected to heat treatment at the sametime as the circulation of blood will be reduced so that a moreefficient and deeply penetrating heat destruction can be obtained.However, it is important that uterus will not be subjected to anexcessive pressure which can cause damage through tissue failure. It hasbeen found that a suitable pressure lies within the range about 100 to140 mm Hg. Higher pressures can be used but the pressure should notexceed abouth 170 to 180 mm Hg. Even if for example such a device forfine adjustement of the pressure as described in connection with FIG. 4will be used the steep increase in pressure at a small change of volumeconstitutes a problem, inter alia in view of the fact that the livingmuscle does not give a constant resistance. In certain cases strongcontractions arise in the muscle, which could result in a drasticincrease pressure if a rapidly acting pressure release cannot beprovided.

It is conceivable to arrange for servo control of the device for fineadjustment as described so that the pressure can be maintained betweentwo pre-determined values, but such system is complicated and is notalways rapid enough in order to compensate for for example musclecramps.

FIG. 13 shows a pressure control device which in a simple and efficientmanner provides for facilitated adjustment of pressure and enablespressure release upon sudden pressure increase resulting from forexample contraction of uterus. Said control means designated 101 hasbeen added to =he the disposable part 7 shown in FIG. 1, via a secondside conduit 103 connected to side conduit 16 of the disposable part 7.Control device 101 contains a central tube 105 provided with holes 107.Said tube 105 is surrounded by an elastic balloon 109 which is therebyconnected to the disposable part 3 so as to be filled with liquid whenthe system is filled using syringe 19. When pressurizing the systemelastic balloon 109 then expands, such as to the position 109′ shown infull line in FIG. 13.

In accordance with the invention there is selected for balloon 109 anelastic material of for example silicon. The plateau pressure of saidmaterial is substantially higher than the plateau pressure for enclosure23 but somewhat higher or equal to the pressure suitable for thetreatment.

The pressure/volume relation for a suitable material is shown in FIG. 12by curve 12 in dotted line. As is clear from FIG. 12 the plateaupressure lies within the range about 180 to 200 mm Hg.

The system including pressure control device 101 is pressurized asdescribed in connection with FIGS. 4 and 5, but the pressure/volumerelation will be different in view of the fact that also balloon 109will expand during the pressure increase.

FIG. 12 shows how the pressure increase AC changes to AE and how thepressure increase BD changes to BF. The change obtained by adding thepressure control device 101 to the system results on the one hand in theadvantage that the pressure increase within the range 80 to 150 mm Hg isless steep, i.e. easier to control. On the other hand, the pressureincrease at pressures exceeding about 160 mm Hg is very slow. In thiscase a suitable operating pressure is about 150 to 160 mm Hg. This meansfor example that at a sudden contraction of uterus the pressure increasefrom the pre-set pressure will be relatively small so that damages touterus can be prevented. The reason as to why drastic pressure increasecan be prevented is the fact that if enclosure 23 will be compressedthrough contraction of uterus a corresponding quantity of liquid will betransferred to balloon 109. If the contraction of uterus ceases acorresponding quantity will be transferred back from balloon 109 toenclosure 23.

As is clear from the above description the supplementary equipmentresiding in pressure control device 101 is simple end and cheap inmanufacture and belongs to the part of the equipment that is disposed ofafter use.

In certain cases it can be of advantage to be able to vary the plateaupressure of the balloon 109. This can be done by surrounding balloon 109with an airtight container 111 shown by the dashed square in FIG. 13.Container 111 can be provided with pressurizing means, such as a manualoperated pump, not shown it FIG. 13. By pressurizing container 111 theplateau pressure of balloon 109 can be set at the desired value. In thismanner different plateau pressures can be obtained using one and thesame balloon 109.

We claim:
 1. An apparatus for effecting hyperthermia in a body cavity orduct comprising: a disposable first part comprising an elongate distalsection intended to be inserted into said cavity or duct comprising acentrally located, heat-releasing element, which is either surrounded byan elongate housing or is itself constituted by an elongate housing, anda flexible and/or elastic enclosure surrounding said housing in aliquid-tight manner, further including means for supplying energy to theheat-releasing element and an axially operating first inlet at theproximal part of the housing, an outlet from the housing being arrangedfor the supply of heat-transmitting medium under pressure for expansionof the flexible enclosure to accommodate and to exert a controllerpressure on surrounding walls of said cavity or duct, a second inlet tothe housing, and a medium-actuating means for said expansion of theflexible enclosure and for internal circulation of said medium in aclosed circuit from said second inlet through the housing exiting viasaid outlet and flowing on an outside of said housing to return to saidsecond inlet; and a permanent non-disposable second part comprisingdrive means for said means for expansion and for internal circulation,and connecting means for releasably inter-connecting said drive meansand said means for expansion and internal circulation, saidmedium-actuating means comprising a first means for the expansion of theflexible enclosure, and a second means for the internal circulation ofthe medium through the housing, said first means being capable also ofremoving medium from the system to bring the enclosure into a collapsedcondition.
 2. An apparatus according to claim 1, wherein said secondmeans comprises a reciprocating element creating a reciprocating motionto a determined quantity of the pressurized medium.
 3. An apparatusaccording to claim 2, wherein said reciprocating element is part of asyringe.
 4. An apparatus according to claim 1, wherein said first meansis constituted by a syringe.
 5. An apparatus according to claim 1,wherein said drive means comprise a first device capable of creatingreciprocating motion for transfer to said reciprocating element via saidconnecting means.
 6. An apparatus according to claim 5, wherein saiddevice comprises an eccentric.
 7. An apparatus according to claim 4,wherein said drive means additionally comprise a second drive capable ofaxial adjustment of an end plate of said reciprocating element via saidconnecting means.
 8. An apparatus according to claim 7, wherein saidsecond device is capable of providing both major adjustment, such as forfilling the system under expansion of the enclosure, and fine adjustmentfor setting a desired pressure.
 9. An apparatus according to claim 1,wherein said first means and said second device, respectively, arecapable of yielding to avoid excessive pressure.
 10. An apparatusaccording to claim 1, wherein said internal circulation allows saidmedium to absorb heat and subsequently release heat in said enclosure.11. An apparatus according to claim 1, comprising at least one firstback valve arranged in association with said second inlet allowing flowinto the interior of housing and the flow resistance of which in an openposition is lower than the flow resistance through housing, said meansfor internal circulation being arranged to provide a reciprocatingmovement of a small quantity of the pressurized medium enclosed in theinlet canal of the device after expansion of the enclosure, whereby theinlet is closed and the outlet is open, thereby providing circulation ofthe medium in a closed circuit.
 12. An apparatus according to claim 1,comprising at least one first back valve arranged in association withthe outlet allowing flow out of the interior of housing, the flowresistance of the inlet being higher than the flow resistance throughhousing, said means for internal circulation being arranged to provide areciprocating movement of a small quantity of the pressurized mediumenclosed in the inlet canal of the device after expansion of theenclosure, whereby the inlet is open and the outlet is closed, therebyproviding circulation of the medium in a closed circuit.
 13. Anapparatus according to claim 1, comprising oppositely operating backvalves arranged in association with said outlet and said second inlet,respectively.
 14. An apparatus according to claim 1, wherein saidheat-releasing element is of an inherently self-regulating type.
 15. Anapparatus according to claim 14, wherein said medium-actuating meanscomprise a first means for the expansion of the flexible enclosure, anda second means for the internal circulation of the medium through thehousing.
 16. An apparatus according to claim 15, wherein said firstmeans is capable also of removing medium from the system to bring theenclosure into a collapsed condition.
 17. An apparatus according toclaim 15, wherein said second means comprises a reciprocating elementcreating a reciprocating motion to a determined quantity of thepressurized medium.
 18. An apparatus according to claim 15, wherein saidreciprocating element is part of a syringe.
 19. An apparatus accordingto claim 15, wherein said first means is constituted by a syringe. 20.An apparatus according to claim 1, further comprising a seconddistensible and elastic enclosure, the interior of which is incommunication with the interior of said flexible enclosure, whereby anyundesired pressure arising in the flexible enclosure will be releasedthrough distention of said second enclosure.
 21. An apparatus accordingto claim 20, wherein said second enclosure has a higher resistance todistention than the flexible enclosure.
 22. An apparatus according toclaim 20, comprising a non-elastic container surrounding said secondenclosure, and means for controlling the pressure within said containerand exterior to said second enclosure, whereby the level of release ofsaid excessive pressure can be adjusted.
 23. An apparatus comprising: adisposable section including: a first housing, substantially surroundedby a flexible enclosure, having a heat releasing element disposedtherein; tubing connected to said first housing and, said flexibleenclosure at a distal end thereof; at least one fluid pressurizingdevice for pumping a fluid through said tubing at a proximal end thereofand into said flexible enclosure via said first housing; anon-disposable section including: a second housing; at least oneretaining means within said second housing for releasably retaining saidat least one fluid pressurizing device; at least one drive means,operably connected with said at least one fluid pressurizing means whensaid at least one fluid pressurizing device is retained within said atleast one retaining means, for powering said fluid pressurizing deviceto provide internal circulation of said fluid within said apparatus;wherein said internal circulation provides for an intake of said fluidthrough an inlet in said first housing and moving said fluid past saidheat releasing element, said fluid exiting said first housing at anoutlet and returning to said inlet.
 24. The apparatus of claim 23,wherein said at least one retaining means further comprises a bed forreceiving said at least one fluid pressurizing device and a slot forreceiving a flange associated with said at least one fluid pressurizingdevice.
 25. An apparatus comprising: a disposable section including: afirst housing, substantially surrounded by a flexible enclosure; tubingconnected to said first housing and, said flexible enclosure at a distalend thereof; at least one fluid pressurizing device for pumping a fluidthrough said tubing at a proximal end thereof and into said flexibleenclosure via said first housing; a non-disposable section including: asecond housing; at least one retaining means within said second housingfor releasably retaining said at least one fluid pressurizing device; atleast one drive means, operably connected with said at least one fluidpressurizing means when said at least one fluid pressurizing device isretained within said at least one retaining means, for powering saidfluid pressurizing device to provide internal circulation of said fluidwithin said apparatus; wherein said internal circulation provides for anintake of said fluid through an inlet in said first housing and movingsaid fluid within said flexible enclosure, said fluid exiting said firsthousing at an outlet and returning to said inlet.
 26. The apparatus ofclaim 25, further comprising a heat releasing element.
 27. The apparatusof claim 25, wherein the at least one drive means further comprises:coarse adjustment means for filling the flexible enclosure with fluid;and fine adjustment means for setting a pressure of the flexibleenclosure.
 28. The apparatus of claim 25, wherein the at least one drivemeans is operably connected with the at least one fluid pressurizingdevice by fluid control means, the fluid control means comprising: meansfor controlling the pressure of the fluid delivered to the at least onefluid pressurizing device; and means for circulating the fluid in the atleast one fluid pressurizing device.
 29. The apparatus of claim 28,wherein the means for circulating the fluid further comprises areciprocating element for causing the fluid to circulate in the at leastone fluid pressurizing device.
 30. The apparatus of claim 28, whereinboth the means for controlling the pressure and the means forcirculating the fluid include a syringe.
 31. The apparatus of claim 26,wherein heated fluid is circulated in the flexible enclosure.
 32. Anapparatus comprising: a heat releasing element; a disposable sectionincluding: a first housing, substantially surrounded by a flexibleenclosure; tubing connected to said first housing and, said flexibleenclosure at a distal end thereof; at least one fluid pressurizingdevice for pumping a fluid through said tubing at a proximal end thereofand into said flexible enclosure via said first housing; anon-disposable section including: a second housing; at least oneretaining means within said second housing for releasably retaining saidat least one fluid pressurizing device; at least one drive means,operably connected with said at least one fluid pressurizing device whensaid at least one fluid pressurizing device is retained within said atleast one retaining means, for powering said fluid pressurizing deviceto provide internal circulation of said fluid within said apparatus;wherein said internal circulation provides for an intake of said fluidthrough an inlet in said first housing and moving said fluid past saidheat releasing element, said fluid exiting said first housing at anoutlet and returning to said inlet.
 33. The apparatus of claim 32,wherein the at least one drive means is operably connected with the atleast one fluid pressurizing device by fluid control means, the fluidcontrol means comprising: means for controlling the pressure of thefluid delivered to the at least one fluid pressurizing device; and meansfor circulating the fluid in the at least one fluid pressurizing device.34. The apparatus of claim 33, wherein the means for circulating thefluid further comprises a reciprocating element for causing the fluid tocirculate in the at least one fluid pressurizing device.
 35. Theapparatus of claim 33, wherein both the means for controlling thepressure and the means for circulating the fluid include a syringe. 36.An apparatus comprising: a heat releasing element; a disposable sectionincluding: a flexible enclosure; tubing connected to said flexibleenclosure at a distal end thereof; at least one fluid pressurizingdevice for pumping a fluid through said tubing at a proximal end thereofand into said flexible enclosure; a non-disposable section including: ahousing; at least one retaining unit within said second housing forreleasably retaining said at least one fluid pressurizing device; atleast one power unit, operably connected with said at least one fluidpressurizing device when said at least one fluid pressurizing device isretained within said at least one retaining unit, for powering saidfluid pressurizing device to provide internal circulation of said fluidwithin said apparatus; wherein said internal circulation provides for anintake of said fluid through an inlet in said fluid pressuring deviceand moving said fluid past said heat releasing element, said fluidexiting said fluid pressuring device at an outlet and returning to saidinlet.
 37. The apparatus of claim 36, wherein the at least one drivemeans is operably connected with the at least one fluid pressurizingdevice by fluid control means, the fluid control means comprising: meansfor controlling the pressure of the fluid delivered to the at least onefluid pressurizing device; and means for circulating the fluid in the atleast one fluid pressurizing device.
 38. The apparatus of claim 37,wherein the means for circulating the fluid further comprises areciprocating element for causing the fluid to circulate in the at leastone fluid pressurizing device.
 39. The apparatus of claim 37 whereinboth the means for controlling the pressure and the means forcirculating the fluid include a syringe.